328 



PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. 



large tabular masses of very ferruginous saudstone and in places 

 to concretionary masses of limonite. Its introduction seems often 

 to have been subsequent to the formation of the beds. At some 

 places the same bed presents a stained and an unstained portion, 

 as in the following section* (fig. 10). 



Fig. 10. — Section in the Cliff at Walton. 



White sand 



^^ "^antl crag. 



The most remarkable result, however, arising from the presence ot 

 iron in these beds is exhibited in a pit near Butley Abbey (fig. 11). 



Here the iron has segregated, not in distinct and separate seams 

 or nodules, but in large sections of the sands, throughout Avhich it has 

 produced a pseudomorphous structure affecting the arrangement of 

 the beds themselves, which show on the one hand the concentric layers 

 due to the mineral action, and on the other the lamination due 

 to the bedding. The masses thus affected are as much as from 

 30 to 40 feet in horizontal diameter, whilst their vertical diameter 

 is but from 3 to 4 feet. The appearance at first sight is as if the 

 beds had been disturbed or reconstructed ; but a closer examination 

 shows that the lines of stratification extend through all the con- 

 centric ferniginous rings. Nevertheless the stratification is subor- 

 dinate to the action of segregation, which has so modified and 

 moulded the beds that the rings or, rather, coats of segregation, when 

 sufficiently consolidated, intersect the slightly consolidated sands and 

 grit just like planes of cleavage in the older rocks, and cause the de- 

 tached layers to peel off in accordance with the structure superin- 

 duced by the presence of the iron, and intersect the bedding at various 

 angles. These concentric rings pass indifferently through beds of 

 sand, grit, and crag, but are cut off sharply or are lost when they 

 come into contact with a seam more highly and entirely ferruginous. 

 It is the most illustrative instance of this kind of action of such 

 magnitude in beds of this class that has come within my knowledge. 



From Walton to Aldborough the lower division of the Red Crag 

 abounds in shell-remains, the greater part comminuted, but with 

 many entire and single valves usually placed with their concave side 

 downwards. Some double shells, especially of Mytilus edulis, As- 

 tarte, Tellina, Mactra, and Corbula, occur, but they are not common. 

 With the exception of the old shore at Sutton, with its Mytili and 



* Possibly the deep ferruginous colour of the Coralline Crag {g) at Sutton is 

 due to a staining received from encircling beds of Red Crag since removed. 



